Disorders associated with the gastrointestinal (GI) and hepatobiliary tracts and the organs/tissues associated with the GI tract include cancers such as gastric cancer, esophageal cancer, liver cancer, and pancreatic cancer. Pancreatic cancer (e.g., pancreatic adenocarcinoma), in particular, is a malignant growth of the pancreas that mainly occurs in the cells of the pancreatic ducts. This disease is the ninth most common form of cancer, yet it is the fourth and fifth leading cause of cancer deaths in men and women, respectively. Cancer of the pancreas is almost always fatal, with a five-year survival rate that is less than 3%.
The most common symptoms of pancreatic cancer include jaundice, abdominal pain, and weight loss, which, together with other presenting factors, are often nonspecific in nature. Thus, diagnosing pancreatic cancer at an early stage of tumor growth is often difficult and requires extensive diagnostic work-up, often times incidentally discovered during exploratory surgery. Endoscopic ultrasonography is an example non-surgical technique available for diagnosis of pancreatic cancer. However, reliable detection of small tumors, as well as differentiation of pancreatic cancer from focal pancreatitis, is difficult. The vast majority of patients with pancreatic cancer are presently diagnosed at a late stage when the tumor has already extended beyond the pancreas to invade surrounding organs and/or has metastasized extensively. Gold et al., Crit. Rev. Oncology/Hematology, 39:147-54 (2001), incorporated herein by reference in its entirety. Late detection of the disease is common with the majority of patients being diagnosed with advanced disease that often results in death; only a minority of patients are detected with early stage disease.
Invasive techniques to diagnose disorders and diseases related to the GI tract are inconvenient and expose a subject to significant risk. Accordingly, there is a need for non-invasive methods and compositions for the detection and identification of target molecules from the GI tract or associated organs/tissues. In some embodiments, the target molecules may be evaluated to determine whether they are useful as biomarkers associated with a particular characteristic, such as disease, predisposition to disease, positive response to a treatment regimen, or no response or negative response to a treatment regimen. In addition, biomarkers from the GI tract or associated organs/tissues may be used to determine whether an individual has any of the particular characteristics listed above.